The ionic compound CaO is called calcium oxide.
Calcium oxide is formed by the combination of calcium ions (Ca2+) and oxide ions (O2-). In this compound, one calcium ion donates two electrons to one oxide ion, leading to an ionic bond. Calcium, a metal from the alkaline earth metal group, readily loses electrons, while oxygen, a non-metal, tends to gain electrons. This transfer of electrons results in the formation of a stable ionic compound that is commonly used in various applications, including construction, agriculture, and chemical manufacturing.